This invention relates generally to branch forming attachments and, more specifically, to a tap having a cutting tube for a one-step connection of a branch line to a main line without the aid of tools.
The concept of forming branch attachments to rigid and plastic tubing is known in the art. Generally, pipe saddles are fastened around a pipe so that one can connect a branch tubing to a main tubing. Attaching a branch tubing to a main tubing often requires numerous steps and sometimes it is difficult to adequately seal the junction between the branch tubing and the main tubing.
The attaching device usually comprises two parts, a tap for forming the opening in the pipe and a saddle for holding the main tubing and the branch tubing in fluid communication. In one application shown in U.S. Pat. No. 5,105,844 a tap or cutter having a through passage both cuts a hole and forms a side attachment for the pipe. In the cutter shown in U.S. Pat. No. 5,105,844 a coupon or plug is cut free of the pipe and is frictionally retained within the cutter so as not to interfere with or block the passageway in the pipe.
In the invention shown in U.S. Pat. No. 5,105,844 the pipe clamp comprises two identical parts that when snapped together form a threaded recess to allow a user to threadingly drive the coupon cutter through the plastic pipe and position a branch pipe in fluid communication with the main tubing.
The self tapping branch attachments are particularly well suited for underground irrigation systems that require in situ forming of branch lines to a main tubing, but they are also useful in other systems and other locations that use rigid, resilient or flexible tubing.
Other branching concepts use a piercing of the main pipe with a pointed tap. One example of such type of a tap is shown in U.S. Pat. No. 3,891,150 that shows an irrigation system that uses a probe with a tapered point that is forced though the sidewall of the main pipe. Another embodiment using a tapered point is shown in U.S. Pat. No. 5,694,972 which shows a saddle tee for an irrigation line and a stem with a tapered point that is punched through the plastic pipe. In the piercing method the tubing can be severely distorted in the region at the junction of the two pipes which can cause leakage.
The pipe clamp used in the U.S. Pat. No. 5,694,972 is also shown in U.S. Pat. No. 4,291,855 and comprises two segments that are hinged at an intermediate point to allow the segments to spread apart and receive a pipe.
In contrast, the present invention has a hollow tap having a cutting tooth is used to form the side attachment passage but instead of cutting the coupon free of the tubing and retaining the coupon in the cutter the coupon is only partially severed from the pipe. The coupon itself forms a living hinge connection to the pipe which retains the coupon in the pipe. The partially severing of the coupon minimizes the distortion of the pipe at the junction of the main pipe and the branch pipe, which can lessen the opportunity for leakage. The partial severing and retaining of the coupon as an integral living hinge ensures that the coupon will not interfere and block any outlet passages in the main tubing. In the event a rigid tubing, such as PVC, is employed with the present invention the tap will cut the coupon free of the tubing since the more rigid PVC will break rather than flex. In this case the coupon can be flushed free of the tubing.
Briefly, the invention comprises a tap having an axially outward extending cutting tooth so that when the cutting tooth is brought into rotational pressure engagement with a resilient tubing the cutting tooth cuts a hole partially through the resilient tubing leaving a coupon integrally hinged but securely attached to the resilient tubing to maintain the coupon in an out-of-the-way condition within the passageway of the resilient tubing. Continued rotation of the tap within a saddle brings a sealing surface on the cutting tube into a fluid tight seal with the sidewalls of the cut opening in the resilient tubing to provide a branch outlet to the resilient tubing though the tap with a minimum of pipe distortion around the junction of the main pipe and the sealing surface of the tap. By rotation of the tap through the pipe one avoids the distortion produced by radially piercing the pipe with a sharp point.
U.S. Pat. No. 1,181,131 is a U-bolt pipe saddle with an extra piece required between the main and branch tubing to secure the fit;
U.S. Pat. No. 3,162,211 shows a device with a cutting needle for forming a hole in a pipe.
U.S. Pat. No. 3,240,434 shows an irrigation nozzle with a hollow point that is inserted through an opening in the pipe.
U.S. Pat. No. 3,343,724 shows a similar tap a tap with a needle point and a side port for tapping into the side of a sealed plastic bag.
U.S. Pat. No. 3,349,792 shows a tapping tee and valve.
U.S. Pat. No. 3,448,758 shows a refrigerator service valve that uses a hollow point that is cut at an angle to insert through a pipe.
U.S. Pat. No. 3,460,715 shows a tap with a needle point and a side port for tapping into the side of a sealed plastic bag.
U.S. Pat. No. 3,471,176 is a pipe saddle which does not specify a method for creating the hole for the branch tubing. Most likely, it employs a hand tool;
U.S. Pat. No. 3,891,150 is a pipe saddle not suited for high-pressure or high-wear situations;
U.S. Pat. No. 3,920,937 shows a drip irrigation system which includes a saddle and sharp pointed tube for extending through a pipe.
U.S. Pat. No. 3,973,732 shows a quick fitting that is forced through the wall of the tubing.
U.S. Pat. No. 4,239,265 is a pipe saddle requiring four steps and four different parts as well as a sealing ring;
U.S. Pat. No. 4,291,855 shows a pipe clamp having hinged portions for securing around a pipe.
U.S. Pat. No. 4,789,189 is a metal pipe saddle requiring a cutting tool to make a branch hole, and another device to reseal the hole.
U.S. Pat. No. 5,105,844 shows a two step branch forming attachment with a cutter for cutting a coupon from a main pipe.
U.S. Pat. No. 5,169,177 shows a saddle for mounting around a tube.